Clinical features and Staphylococcus aureus colonization/infection in childhood atopic dermatitis

Staphylococcus aureus (SA) colonization/infection is important in the pathophysiology of childhood atopic dermatitis (AD). This study evaluated which clinical features may predict presence of SA colonization/infection and reviewed antimicrobial sensitivity of SA in patients with AD.

The associations between bacteriologic culture results of skin swabs (taken at the most severely affected area and at the antecubital fossa) and SCORing-Atopic-Dermatitis (SCORAD), skin hydration, transepidermal water loss (TEWL), and quality of life were evaluated.

Moderate-to-heavy growth of SA was present in 31% of the swabs of the most severe area and in 16% of the flexural (antecubital fossae) areas of 95 AD patients (12.5 ± 4.8 years). Binomial logistic regression showed moderate-to-heavy growth of SA in the severe area were associated with objective SCORAD (p = 0.004) and lesion intensity [erythema (p = 0.022) and lichenification (p = 0.035)]; and excoriation (p = 0.024) and TEWL (p = 0.009) in the antecubital fossa. The relative risk of isolating moderate-to-heavy growth of SA in the most affected area in patients with severe disease (objective SCORAD >40) is 2.73 (1.43-5.21, p = 0.001). Any growth of SA in either swab sites was associated with objective SCORAD and lesion intensity (p = 0.001-0.019). SA had no association with quality of life and other clinical parameters. All specimens of methicillin-sensitive SA were sensitive to cloxacillin. All methicillin-resistant SA (MRSA) (5.7%) was sensitive to co-trimoxazole and fusidic acid.

Clinical features, especially severity and lesion intensity, are useful in "predicting" moderate-to-heavy SA colonization/infection in AD patients. Cloxacillin has a favorable sensitivity profile for MSSA, and co-trimoxazole and fusidic acid for MRSA. As colonization and infection are ambiguous and potentially overlapping clinical states, we recommend to abandon these terms and propose to describe quantitatively/semi-quantitatively SA isolation as none, mild, scanty, moderate or heavy growth instead in clinical trials.